kill 

 leep 



SCIENTIFIC SIDE-LIGHTS 



630 



by accident; so that a flint flake, simple 

 as it may seem to the untrained eye, is to 

 the antiquary as sure a trace of man as 

 the footprint in the sand was to Robinson 

 Crusoe. AVEBURY Prehistoric Times, ch. 4, 

 p. 83. (A., 1900.) 



3121. SKINS AS CLOTHING Woman 

 the Skin Dresser of Ancient Times. If aught 

 in the heavens above, or on the earth be- 

 neath, or in the waters wore a skin, sav- 

 age women were found on examination to 

 have had a name for it, and to have suc- 

 ceeded in turning it into its primitive use 

 for human clothing, and to have invented 

 new uses undreamed of by its original 

 owner. ... As any taxidermist, or farm- 

 er's boy, for that matter, knows, there are 

 hosts o'f birds and fish and small mammals 

 whose hides need only to be drawn off and 

 dried wrong side out in the sun to be com- 

 pletely cured. The furrier has his way of 

 keeping out the destructive insects, and the 

 taxidermist knows the virtues of arsenical 

 soap; but away on the boundaries of time 

 or civilization the harmonies of Nature had 

 not been so much disturbed, hence there 

 was not such trouble with insect pests. 

 Furthermore, the garment or what-not was 

 in daily use until it was worn out, so there 

 was poor chance for moths or dermestids. 

 MASON Woman's Share in Primitive Cul- 

 ture, ch. 4, p. 71. (A., 1894.) 



3122. SKULL, PREHISTORIC, 

 MIGHT HAVE BELONGED TO A PHI- 

 LOSOPHER No Mark of Degradation in 

 Engis Skull. Taking the evidence as it 

 stands, and turning first to the Engis skull, 

 I confess I can find no character in the re- 

 mains of that cranium which, if it were 

 a recent skull, would give any trustworthy 

 clue as to the race to which it might ap- 

 pertain. Its contours and measurements 

 agree very well with those of some Austra- 

 lian skulls which I have examined, and es- 

 pecially has it a tendency toward that occip- 

 ital flattening, to the great extent of which 

 in some Australian skulls I have alluded. 

 But all Australian skulls do not present 

 this flattening, and the superciliary ridge 

 of the Engis skull is quite unlike that of 

 the typical Australians. On the other hand, 

 its measurements agree equally well with 

 those of some European skulls. And as- 

 suredly there is no mark of degradation 

 about any part of its structure. It is, in 

 fact, a fair average human skull, which 

 might have belonged to a philosopher or 

 might have contained the thoughtless brains 

 of a savage. HUXLEY Man's Place in Na- 

 ture, p. 253. (Hum.) 



3123. SKY, ARTIFICIAL Composite 

 Particles Too Small for Microscope Infini- 

 tesimal Minuteness. Into an experimental 

 tube I introduce a new vapor, . . . and 

 add to it air which has been permitted 

 to bubble through dilute hydrochloric acid. 

 On permitting the electric beam to play 



upon the mixture, for some time nothing 

 is seen. The chemical action is doubtless 

 progressing, and condensation is going on; 

 but the condensing molecules have not yet 

 coalesced to particles sufficiently large to scat- 

 ter sensibly the waves of light. . . . The 

 particles here generated are at first so small 

 that their diameters do not probably exceed 

 a millionth of an inch; while to form each 

 of these particles whole crowds of mole- 

 cules are probably aggregated. Helped by 

 such considerations, our intellectual vision 

 plunges more profoundly into atomic Na- 

 ture, and shows us, among other things, how 

 far we are from the realization of Newton's 

 hope that the molecules might one day be 

 seen by means of microscopes. While I am 

 speaking, you observe this delicate blue color 

 forming and strengthening within the ex- 

 perimental tube. No sky-blue could exceed 

 it in richness and purity; but the particles 

 which produce this color lie wholly beyond 

 our microscopic range. A uniform color is 

 here developed, which has as little breach 

 of continuity which yields as little evidence 

 of the individual particles concerned in its 

 production as that yielded by a body whose 

 color is due to true molecular absorption. 

 This blue is at first as deep and dark as 

 the sky seen from the highest Alpine peaks, 

 and for the same reason. But it grows 

 gradually brighter, still maintaining its 

 blueness, until at length a whitish tinge 

 mingles with the pure azure, announcing 

 that the particles are now no longer of that 

 infinitesimal size which scatters only the 

 shortest waves. TYNDALL Heat a Mode of 

 Motion, lect. 16, p. 490. (A., 1900.) 



31 24. SKY, CLOUDLESS, CONTAINS 



DUST-PARTICLES Matter from All Lands 

 and from Celestial Spaces. Something, then, 

 in a cloudless sky still exists to reflect the 

 rays toward us, and this something is made 

 up of separately invisible specks of dust and 

 vapor, but very largely of actual dust, which 

 probably forms the nucleus of each mist- 

 particle. That discrete matter of some kind 

 exists here has long been recognized from 

 the phenomena of twilight; but it is, I 

 think, only recently that we are coming to 

 admit that a shell of actual solid particles 

 in the form of dust probably encloses the 

 whole globe, up to far above the highest 

 clouds. 



In 1881 the writer had occasion to con- 

 duct a scientific expedition to the highest 

 point in the territories of the United States, 

 on one of the summits of the Sierra Nevadas 

 of Southern California, which rise even above 

 the Rocky Mountains. . . . Yet even 

 above here on the highest peak, where we 

 felt as if standing on the roof of the con- 

 tinent and elevated into the great aerial 

 currents of the globe, the telescope showed 

 particles of dust in the air, which the geol- 

 ogists deemed to have probably formed part 

 of the soil of China and to have been borne 

 across the Pacific, but which also, as we 



